1. Technical Field
The present invention relates to a cushion and/or a bed overlay, for use in and on wheelchairs and, if constructed as a bed overlay, as a support for short- or long-term patients or as an operating table.
2. History of Related Art
Pressure sores occur as a result of lack of care, especially in the tissue where the patient's weight impairs the circulation of the respective tissue over a lengthy period of time predominantly via individual bones, for example the sacrum, ischia, trochanter. The recognized therapy of choice is either moving the lying patient to another bed or taking care, by apparatus-supported means, that the resting points of the lying or sitting body vary.
Several apparatus-based solutions have been produced in response to this requirement. Many of these solutions operate with transversely and/or longitudinally segmented mattresses for patients' beds. Here, the individual segments are filled alternatingly or rhythmically with a pressure medium—water or air—, and thus bring about changes and movements of the resting or sitting points. Such a bed—as an example of this group of solutions—is described in U.S. Pat. No. 5,267,364 (D1). In D1 a hospital bed is disclosed, which carries on a foam mattress an air mattress. This is segmented into a plurality of individual, transversely-running air pockets which each have an individual air connection and are filled with compressed air in a controllable sequence. Compared with the possible extent of the wounds of pressure sores, the segmenting is relatively crude and only takes place in the longitudinal dimension of the bed. The solution disclosed in D1 is not suitable for preferably seated patients, such as paraplegics or tetraplegics.
The solution known from EP 0 261 830 (D2) shows a refined segmenting of the air mattress compared with D1. The complexity in terms of apparatus as a whole is great and is correspondingly costly.
In U.S. Pat. No. 6,592,533 (D3) a massage bed is described, likewise relatively crudely segmented, where, however, a pressure sore of a patient is not to be given therapy or treated preventively; on the other hand, a changing support of the patient on air cushions and a padding with elastic fibres is envisaged.
EP 1 307 169 (D4) likewise describes a massage chair with a number of mechanically driven massage elements which are each surrounded by a ring-shaped cushion. The cushions are acted upon by a pressure fluid with a controlled pressure. The device is preferably constructed as a massage chair with massage elements also in the region of the thoracic vertebrae. The complexity in terms of apparatus is great and would scarcely be able to be integrated into a wheelchair.
Finally, from WO 2004/037 148 (D5) a cushion is known for the palliation of pressure sores, with a foam support onto which a fluid mattress is placed. This fluid mattress is divided into reciprocally fluid-tight strips. Several fluid pumps control the pressure and the frequencies of pressure change.